This invention relates to apparatus for mounting solid state devices, and more particularly to such apparatus which permits effective heat sinking of power solid state devices mounted on a printed circuit board or the like.
Present techniques for mounting solid state devices contemplate either small clip-on type heat sinks clipped to the packages or "cans" housing the devices, as in the case of the small finned type heat sinks which are used with certain standard device packages, or the larger, extruded aluminum or aluminum alloy sinks to which devices are attached using screws or nuts and bolts, typically with mica insulators interposed between electrically conductive portions of the device package and the extrusion. In such cases, the bolt or screw which passes through an electrically conductive portion of the device package and through the extrusion must be insulated from one or the other of these to prevent inadvertent electrical contact between the device package and the extrusion. This is sometimes done with a grommet or sleeve of insulating material which is slipped onto the screw or bolt and a insulative material-type washer. As will be appreciated, this involves a fairly complicated assembly process. Additionally, distances between components, such as the electrically conductive portion of the package and the screw or nut and bolt which attach it to the extruded heat sink and the heat sink itself, are rather small. These distances cannot be very carefully regulated because of the assembly process required. Therefore, when high voltages appear on the electrically conductive components of the package, the possibility of arcing across these relatively small spaces, the exact length of which cannot be carefully controlled, becomes significant.